1. Field of the Invention
The invention concerns a process and a device for detecting and monitoring a number of vehicles driving ahead of one""s own vehicle.
2. Description of the Related Art
A process of this type serves for assisting the operator of a vehicle during lane change, for example for merging into or exiting from a highway or for passing a slower vehicle. Beyond this the process serves for conforming the speed of the own vehicle to the speed of one of the preceding vehicles in one""s own lane.
This type of process is known for example from DE 43 13 568 C1. Therein for guidance assisting in a lane change the preceding space and the rearward space of the adjacent target lane is monitored for determining the distance of objects. The necessary safety distances are maintained, and corresponding lane change opportunities are recognized. As monitoring detectors there are known, in addition to ultrasound and infrared devices (see for example DE 38 32 720 A1), also radar devices for monitoring the so-called blind zone (see for example DE 39 02 852 A1) and for measuring the distance with respect to preceding vehicles to enable driving with automatic maintenance of distance or interval (see EP 0 501 345 A2).
The known processes always take into consideration a preceding vehicle in only a very narrow limited area, for example in the directly preceding area (=own lane) or in an adjacent area (=adjacent lane). In the case that this preceding vehicle leaves the monitored area, monitoring is no longer possible. In particular in cases such as multi-lane roadways, in which driving occurs at different speeds in the various lanes, a monitoring of all preceding vehicles is not possible.
The invention is thus concerned with the task of providing a process and device for monitoring a number of preceding vehicles, which substantially unburdens the vehicle operator of the task of monitoring the preceding environment as well as estimating distances and speeds.
The first mentioned task is inventively solved by a process for detecting and monitoring a number of vehicles preceding one""s own vehicle, in which the surrounding environment is divided into at least one near zone and at least one distant zone, wherein the lane, speed and/or distance of the respective preceding vehicles is determined relative to the monitoring vehicle and, on the basis of the respective determined lane, speed and/or distance for the respective preceding vehicles, their positions with respect to the near zone or the distant zone is determined, and wherein the actual speed of the monitoring vehicle (=own speed) is adjusted on the basis of the respective determined speed and/or position of the preceding vehicles.
By monitoring the near zone with a broad aperture angle and the distant zone with narrower aperture angle, objects, in particular vehicles, are detected over the entire breadth of a roadway with multiple lanes and monitored with respect to their operating parameters, such as for example speed, distance and/or position, relative to the monitoring vehicle. Therein the respective positions of the preceding vehicles is preferably monitored on the basis of the associated angle of sight with respect to the longitudinal axis of the monitoring vehicle. For example, the angle of sight for the vehicles preceding the monitoring vehicle in the same lane is 0xc2x0. For preceding vehicles in adjacent lanes there is an angle of sight which is greater than 0xc2x0, and which depends also upon the distance to the monitoring vehicle, and from this information the position of the preceding vehicle is determined. The operator of the monitoring vehicle is thereby substantially relieved of the simultaneous monitoring of multiple vehicles and the burden of processing the flood of information associated therewith, that is, estimation of the various speeds and distances of multiple vehicles, as well how to adapt or conform the driving relationship of the monitoring vehicle thereto. In particular, the driver of the monitoring vehicle is in supported in a simple way and manner in the observation and judging of the preceding traffic situation. Besides this it becomes possible, by the detection of preceding vehicles in the near range zone in adjacent lanes, and by monitoring these vehicles according to the national regulations, to undertake a passing maneuver of these vehicles. That is, in countries in which passing on the left or the right side is forbidden, the speed of the vehicle is adapted depending upon the own position and the position of the preceding vehicle in such a manner, that when passing is forbidden the instantaneous (actual) speed is appropriately restricted. If however passing is allowed, then the actual speed is increased to the maximal permitted speed and the monitoring vehicle accelerates for passing.
In given cases the change in lanes of a preceding vehicle is detected. Preferably, the actual speed of the monitoring vehicle is accelerated or decelerated depending upon the lane change of the preceding vehicle. By the detection of the lane change of a preceding vehicle as well as the further monitoring of this vehicle, a mistake in passing of this vehicle is prevented.
The second above mentioned task is inventively solved by a device for detecting and monitoring a number of vehicles driving in advance of the monitoring vehicle including a first sensor with a first aperture angle or sweep for detecting preceding vehicles in the near range zone, and a second sensor with a second aperture angle or sweep for detecting preceding vehicles in a far range zone, wherein the first aperture angle is larger than the second aperture angle, and with an assisting unit for conforming the actual speed and/or the actual distance of the own vehicle on the basis of the position and/or speed of the preceding vehicles.
Preferably, the first aperture angle covers an area of from 20xc2x0 to 180xc2x0. Thereby in particular every vehicle can be detected, which in the case of a multi-lane road is in the immediate neighborhood on adjacent lanes. Therewith the driving condition of the monitoring vehicle can be adapted to the overall preceding vehicle situation. In particular in the case of a traffic jam in a multi-lane roadway, in which at least two preceding vehicles are detected and monitored in the near zone, the vehicle operator is relieved in a particularly advantageous and simple manner of the task of monitoring and judging the complex advanced vehicle situation.
Preferably, the second aperture angle covers an area of from 3xc2x0 to 30xc2x0. This makes it possible, at high speeds of the monitoring vehicle, to monitor the preceding environment with the greatest possible range. More particularly, the monitoring of the immediately preceding environment, that is, the vehicle lane of the monitoring vehicle, up to the range of approximately 200 meters is made possible. Preferably, as the second sensor, a wide angle sensor, a radar unit, an optical camera or a laser scanner is provided. As first sensor a long range radar is preferably provided.
The advantages achieved in accordance with the invention are comprised in particular therein, that by a combination of the monitoring of near and distant zones with wider or as the case may be narrower aperture angles, a lateral detection of preceding vehicles is made possible. Therewith preceding vehicles, both in the left as well as in the right lane, can be detected simultaneously and discriminated from each other. Therewith the overall preceding traffic situation is monitored and the monitoring vehicle relationship is appropriately conformed. The operator of the monitoring vehicle is thereby substantially unburdened. Beyond this, the vehicle operator is supplementally or alternatively signaled of a possible dangerous or hazardous situation by an acoustic and/or optical signal or some other indication. It is further possible that, by means of the process, while driving on multi-lane roads when passing is permitted only on the left or on the right or on both sides, the legal and optimal lane for passing at any instant is indicated. Alternatively an unpermitted passing is prevented by braking of the monitoring vehicle.